MEDICINES. 397 



which the oil of turpentine and laudanum may be administered in cases of 

 choh'c. 



Myrrh may be used in the form of tincture, or it may be united to the 

 tincture of aloes as a stimulatinp: and digestive apphcation to wounds. 

 Diluted with an equal quantity of water, it is a good application for 

 canker in the mouth, but as an internal medicine it seems to be inert. 



Nitre. — See Potash. 



Nitrous ^ther, Spirit of, is a very useful medicine in the advanced 

 stages of fever, for while it to a certain degree rouses the exhausted 

 powers of the animal, and may be denominated a stimulant, it never 

 brings back the dangerous febrile action which was subsiding. It is 

 given in doses of three or four drachms. 



Oils. — The farrier's list contains many of them, but the scientific prac- 

 titioner has discarded the greater part; those that are worth retaining will 

 be found under the names of the vegetables from which they are extracted. 



Ointments. — These have been fully described under the accidents and 

 diseases in which their use is required. 



Olives, Oil of. — This is sometimes given as a purgative when aloes 

 or other aperients cannot be obtained. It is useless to give it in a less 

 quantity than a pint, and then it is uncertain in its operation, although 

 harmless. In all liniments and ointments, spermaceti, or even linseed 

 oil, may be substituted without detriment, and the peculiar smell of the 

 latter may be subdued by oil of aniseseed or origanum. 



Opium. — However underrated by some, there is not a more valuable 

 drug on our list. It does not often act as a narcotic except in enormous 

 doses; but it is a powerful antispasmodic, sedative, and astringent. 

 As an antispasmodic, it enters into the cholic drink, and it is the sheet 

 anchor of the veterinarian in the treatment of tetanus or locked jaw. As 

 a sedative, it relaxes that universal spasm of the muscular system, which 

 is the characteristic of tetanus ; and perhaps it is only as a sedative that it 

 has such admirable effect as an astringent ; for when the irritation about 

 the mouths of the vessels of the intestines and kidneys is allayed by the 

 opium, undue purging and profuse staling are necessarily arrested. It 

 should, however, be given with caution. It is its secondary efFect which 

 is sedative, and, if given in cases of fever, its primary effect in increasing 

 the excitation of the frame is marked and injurious. In the early and 

 acute stage of fever, it would be bad practice to give it in the smallest 

 quantity ; but when the fever has passed, or is passing, there is no- 

 thing which so rapidly subdues the irritability that accompanies extreme 

 weakness ; and it becomes an excellent tonic, because it is a sedative. 



If the blue or green vitriol, or cantharides, have been pushed too far, 

 opium soonest quiets the disorder they have occasioned. It is given in 

 doses of one or two drachms ; either the powdered opium being made into 

 a ball, or the crude opium, dissolved in hot water, and given with its sedi- 

 ment. Other medicines are usually combined with it, according to the 

 circumstances of the case. 



Externally, it is useful in ophthalmia. In the form of decoction of the 

 poppy head it may constitute the basis of an anodyne poultice ; but it must 

 not be given in union with any alkali, with the exception of chalk, in over- 

 jnirging; nor with the superacetate of lead, by which its powers are mate- 

 rially impaired, nor with sulphate of zinc, or copper, or iron. 



From its high price it is much adulterated, and it is rare to meet with it 

 in a state of purity. The best tests are its smell, its taste, its toughness 

 and pliancy, its fawn or brown colour, and its weight, for it is the heaviest 

 of all the vegetable extracts, except gum arabic ; yet its weight is often 



